You need to train a retrieve and really this should be done from day one.
Before you let him loose on rabbits, you need to know he will bring them back TO YOU.
Get a rabbit skin and stitch it around a small pop bottle filled iwth sand. Have him play and retrieve this and if he starts the 'ooh look here it is, nah im running off wtih it chase me' game, DO NOT CHASE HIM. Just walk away.
You also need to teach him a 100% recall. Again something that you should have been working on from day one.
Whenever you feed him or want him and are going to reward him nicely, use your recall command (not his name). Make sure that is rock solid EVERYWHERE.
So presuming your dog has a first class recall and retrieve, then YOU need to learn how to kill a rabbit. Your lurcher shouldnt do this for you, he should bring back live to hand and you kill the rabbit humanely. Its much better this way than to attempt or hope that the dog will kill the rabbit quickly and have him fail.
If neither of you can bring yourselves to do that, then stop right there and dont teach your lurcher to catch bunnies.
If your dog really is able and willing to do the job, then next you introduce him to some easy catches.
Take him on land where YOU have permission, and make sure there are no risks such as roads and railways etc. You want young rabbits or myxy rabbits to start with as an fully grown rabbit has a hell of a kick and may well scream and bite, all things that will put your young dog off possibly for life.
Dont over do it, let him see the quarry but not have it for a few days. Dont rush him, and when you think hei s keen, let him go.
If he starts playing around then id suspect he isnt up to the job. If he tries and fails reward him well and if he catches, similar, call it a day and go home.
Dont over face a young dog by pushing him hard and expecting him to catch hundreds of rabbits each time out. It has to be fun for him, if its NOT you may well find he isnt interested, or he invents his own games, such as catching rabbits and running off with them.
Can i ask WHY do you want him to work?